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Abstract:

A freight loading system may include: freight transport devices each with
at least one roller for transporting freight items in a transport
direction and each sensor for detecting the presence of a freight item,
wherein the rollers of at least a first freight transport device are
mounted rotationally mobile such that the transport direction of the
first freight transport device is adjustable, and a control unit which
receives signals from sensors of at least two freight transport devices
in order to detect a movement, of a freight item, wherein the control
unit is designed to calculate from the signals a relative movement of
part of the freight item relative to the first freight transport device
and align the at least one roller of the first freight transport device
taking into account the relative movement of the part of the freight
item.

Claims:

1. A freight loading system for loading and unloading a cargo deck
comprising: a multiplicity of freight transport devices each with at
least one roller for transporting freight items in a transport direction
and each with at least one sensor for detecting the presence of a freight
item, wherein the freight rollers of at least one first freight transport
device are mounted rotationally mobile such that the transport direction
of the first freight transport device is adjustable; and a control unit
which receives signals from sensors of at least two freight transport
devices in order to detect a movement, in particular a movement
direction, of a freight item wherein the control unit is designed to
calculate from the signals a relative movement of a part of the freight
item relative to the first freight transport device and align the at
least one roller of the first freight transport device taking into
account the relative movement of the part of the freight item to at least
one of: reduce and minimise the friction of the roller.

2. The freight loading system according to claim 1, wherein the control
unit is designed to align the first freight transport device while the
roller lies by force fit against part of the freight item in order to
drive the freight item.

3. The freight loading system according to claim 1, wherein the control
unit comprises a memory device which stores the data relating to the
position of the sensors relative to each other and on the cargo deck
wherein the control unit is designed to calculate the relative movement
of the part of the freight item using the data from the memory device.

4. The freight loading system according to claim 1, wherein the control
unit is designed to perform a method for determining a movement of a
freight item on a cargo deck comprising: determining at least one of: the
dimensions and shape of a base surface of the freight item by a control
unit; receiving a multiplicity of first signals from sensors which are
arranged distributed over at least part of the cargo deck, wherein the
first signals indicate coverage the freight item at a first time;
calculating the control unit of a first position of the freight item from
the first signals taking into account at least one of: the dimensions
shape of at least the base surface; storing the first position of the
freight item in a memory; receiving a multiplicity of second signals from
the sensors at a second time; calculating the control unit of a second
position of the freight item from the second signals taking into account
at least of: the dimensions shape of the base surface; and calculating
the movement of the freight item by comparison of the first position of
the freight item with the second position.

5. The freight loading system according to claim 1, wherein the control
unit is designed to detect a dimension of a base surface of the freight
item and process this to determine at least one of: a position of the
freight item and the relative movement of the part of the freight item.

6. The freight loading system according to claim 1, wherein the sensors
comprise light sensors arranged on the cargo deck and designed such that
they detect at least the presence of a freight item.

7. The freight loading system according to claim 1, wherein at least one
of either the sensors and multiplicity of freight transport devices, are
arranged in a matrix spanning the width of the cargo deck.

8. The freight loading system according to claim 1, wherein at least some
of the freight transport devices each comprise at least one sensor which
is arranged static relative to the cargo deck.

9. The freight loading system according to claim 1, wherein the sensors
are arranged on a respective freight transport device are arranged
surrounding the at least one roller.

10. The freight loading system according to claim 1, wherein the signals
give a binary coverage pattern.

11. The freight loading system according to claim 1, wherein the first
freight transport device comprises at least one rotary table arranged in
a frame rotatable about a vertical axis and which accommodates at least
one roller in order to set the roller to transport the freight item in a
pre-specified transport direction.

12. The freight loading system according to claim 1, further comprising a
read device, to detect at least one of either: the freight item type and
at least one dimension of the freight item.

13. The freight loading system according to claim 1, wherein the control
unit comprises a model generator to produce: at least one of a
two-dimensional, and three-dimensional, model of the freight item, and at
least part of the hold of the aircraft.

14. The freight loading system according to claim 1, wherein the control
unit comprises a memory device configured to store position data in a
temporal sequence indicating the position of the freight item on the
cargo deck, wherein the control unit is designed to determine the
movement of the freight item from the determined actual position and the
stored position data from the position memory device.

15. The freight loading system according to claim 1, wherein the control
unit is designed to determine a nominal position and an actual position
of the freight item and control at least one freight transport device
such that the freight item is transported out of the actual position into
the nominal position.

16. The freight loading system according to claim 1, wherein the control
unit is designed to determine from the actual position and nominal
position a nominal transport direction (s) for at least one freight
transport device.

17. The freight loading system according to claim 1, wherein the control
unit is designed to determine, taking into account the relative movement,
an optimum transport direction for at least one freight transport device
wherein when assuming the optimum transport direction the axis of the
roller of the respective freight transport device runs substantially
perpendicular to the relative movement of the freight item lying on the
roller.

18. The freight loading system according to claim 1, wherein the control
unit is designed to calculate a set transport direction from the optimum
transport direction and the nominal transport direction (s), and align
the at least one freight transport device according to the optimum
transport direction.

19. The freight loading system according to claim 1, wherein the control
unit is configured: to determine, preferably in real time, the relative
movement of the freight item close to or at the position at which the at
least one roller of the at least one freight transport device makes
contact and determine a nominal transport direction (s); and to align the
roller taking into account the relative movement of the freight item and
the nominal transport direction (s).

20. A method for determining a movement of a freight item on a cargo deck
comprising: determining at least one of: the dimensions and shape of a
base surface of the freight item by a control unit; receiving a
multiplicity of first signals from sensors which are arranged distributed
over at least part of the cargo deck, wherein the first signals indicate
coverage by the freight item at a first time; calculating the control
unit of a first position of the freight item from the first signals
taking into account at least one of: the dimensions and shape of at least
the base surface; storing the first position of the freight item in a
memory; receiving a multiplicity of second signals from the sensors at a
second time; calculating the control unit of a second position of the
freight item from the second signals taking into account at least one of:
the dimensions and shape of the base surface; and calculating the
movement of the freight item by comparison of the first position of the
freight item with the second position.

21. The method according to claim 20, wherein the alignment by the
control unit of at least one freight transport device takes into account
the movement of the freight item.

22. The method according to claim 20, further comprising reading of a
memory mounted on the freight item by means of a reader to determine at
least one: the dimension and shape of at least the base surface of the
freight item.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to German Patent Applications No.
10 2010 060 145.4, filed Oct. 25, 2010 and 10 2011 000 743.1, filed Feb.
15, 2011, priority is claimed to these applications and the disclosures
of these applications are incorporated by reference in their entirety.

BACKGROUND

[0002] The invention relates to a freight loading system for loading and
unloading a cargo deck and a method for determining a movement of a
freight item on a cargo deck of an aircraft.

[0003] For air freight transport, the freight items to be transported, in
particular containers or pallets which are preferably made to specific
standards, are attached inside the hold by means of lock elements on the
cargo deck of the hold. Such lock elements frequently form freight
loading tracks between which the standardised freight items can be
positioned. To position the freight items at the locations provided for
them, freight loading systems are used which support the ground staff in
loading and unloading. These freight loading systems accelerate the
loading and unloading process. Furthermore the freight loading systems
must be very simple to operate as ground staff frequently have no
training in a particular freight loading system. In addition both loading
and unloading take place under high pressure of time, whereby incorrect
operation can easily occur.

[0004] A faulty freight loading system, either because of incorrect
operation or because of natural wear, can lead to substantial costs as it
is very costly to shut down high capacity aircraft. Every minute which a
high capacity aircraft spends on the ground costs the operator money.

[0005] Frequently freight items are loaded onto a cargo deck which has
dimensions such that it is necessary to rotate the freight items, in
particular in the area near the door. For this, the area near the
door--called the loading and unloading area--is fitted with special
function elements comprising freight transport devices (e.g. PDU's, power
drive units) and roller mats. There are various strategies for rotating
freight items in the physically very restricted loading and unloading
area. Corresponding freight loading systems for rotating freight items
are known from U.S. Pat. No. 4,050,655, DE 10 2005 008 443 B4, DE 10 2005
021 078 B4, DE 10 2008 052 468 A1 and DE 101 58 298 C1.

[0006] It has been shown that irrespective of strategy used to rotate the
freight item on the cargo deck, the freight transport devices used are
subject to very high wear. Furthermore the process takes a lot of time.

[0007] In a design consideration of the freight loading systems used here,
it has been found that the loading and unloading area must be designed in
a very complex manner. Here frequently freight transport devices of very
large dimensions must be used which require separate sealing.

SUMMARY OF THE INVENTION

[0008] Some embodiments in accordance with the present invention specify
an improved freight loading system for loading and unloading an aircraft
cargo deck.

[0009] In particular this may be achieved by a freight loading system for
loading and unloading a cargo deck, in particular an aircraft deck,
wherein the freight loading system may include: a multiplicity of freight
transport devices each at least with one roller for transporting freight
items in a transport direction and each with at least one sensor for
detecting the presence of a freight item, wherein the rollers of at least
one first freight transport device are mounted rotationally mobile such
that the transport direction of the first freight transport device can be
set, and a control unit which receives signals from sensors from at least
two freight transport devices in order to detect a movement, in
particular a movement direction, of a freight item, wherein the control
unit is designed such that a relative movement of a part of the freight
item relative to the first freight transport device can be calculated
from the signals and the at least one roller of the first freight
transport device can be aligned taking into account the relative movement
of the part of the freight item, in particular to reduce and/or minimise
the friction of the roller.

[0010] Some embodiments may detect the movement of the item of freight
transported on the cargo deck and use the information obtained to
transport the freight item in a controlled and efficient manner. In
conventional freight loading systems, the aim is to move the freight item
by suitable control of the freight transport devices along prespecified
movement tracks. Deviations for example because of the starting position
always remain disregarded in the control of the freight transport
devices, so that heavy wear occurs from time to time.

[0011] The present invention detects the actual movement of the freight
item and uses the information to load the freight item optimally in the
aircraft hold.

[0012] The information can be used firstly to adjust the rollers passively
in order to reduce wear on the rollers. Secondly the information can be
used to implement an active control strategy, wherein an actual relative
movement of the freight item is compared with a nominal transport
direction so that an optimum transport direction can be determined at
least from these parameters.

[0013] The at least one roller of the first freight transport device,
which preferably can swivel out of a rest position into a drive position
to transport the freight item, can lie by force fit against a section of
the freight item to drive the freight item. Methods for loading and
unloading freight items are known from the prior art, in which the
freight transport devices can swivel between a lowered rest position and
a raised drive position, where in the drive position the roller lies in
force fit against the freight item. To modify the transport direction of
the freight item, frequently the freight item is stopped, the rollers of
the freight transport device lowered, their alignment corrected and then
the drive position resumed so that the freight item can be transported in
another direction. This procedure is very complex. The present invention
proposes making a continuous direction change wherein the roller of the
first freight transport device at least part of the time during alignment
lies with force fit against the freight item. Preferably the roller is
aligned while constantly maintaining the force fit connection.

[0014] Preferably the drive rollers are arranged as close as possible to a
rotation axis of the freight transport device so that on re-alignment
thereof--possibly with force fit--as little friction as possible occurs.

[0015] Preferably the rollers of the freight transport devices are
arranged such that their axes stand perpendicular to the rotation axis of
the freight transport device concerned.

[0016] Preferably the rollers are re-aligned while being driven, in
particular in real time.

[0017] The control unit can comprise a memory device which stores data in
relation to the positions of the sensors relative to each other and/or
the cargo deck (absolute positions), wherein the control unit is designed
to calculate the relative movement of the part of the freight item using
and/or taking into account the data from the memory device. In the end it
is useful if the control unit knows the relative positions of the
individual sensors and/or freight transport devices comprising the
sensors, so that the signals from the sensors can be allocated to a
particular location or position. Thus the control unit is able to
establish which sections of the cargo deck are covered by a particular
item of freight so that at least a rough position of the freight item can
be derived.

[0018] The control unit can be designed to detect a dimension of a base
surface of the freight item and process this to determine the position of
the freight item. It is possible to detect the movement of the freight
item by the provision of complex sensor means. Preferably however such
complex sensor means are omitted, wherein the control unit uses
additional information for example in the form of the dimension of the
base surface of the freight item to achieve as accurate a result as
possible.

[0019] For example the sensors can comprise light sensors which are
arranged and formed on the cargo deck such that they detect at least the
presence of the freight item passing over the sensor. Such sensors are
adequately known in the specialist area and are very robust so that they
will resist for a long time the aggressive conditions which occur in a
hold. The light sensors can be arranged and formed such that they can
detect the area immediately above the light sensor and determine whether
part of the freight item is present in this area. To this extent the
sensor can establish when a freight item is passing over it. Other sensor
means for example mechanical sensor means are conceivable.

[0020] At least some of the sensors can be arranged in a matrix pattern
spanning the cargo deck width, preferably in the loading and unloading
area of the cargo deck. Preferably the sensors, in particular the light
sensors, are distributed widely over the part area, preferably the
loading and unloading area of the cargo deck, so that at different points
on the cargo deck it can be established whether a part section of the
freight item is present. To this extent the sensors can be used to
determine the position of the freight item at a particular time.

[0021] At least some of the freight transport devices can comprise at
least one sensor, preferably at least four sensors to detect the freight
items.

[0022] At least some of the freight transport devices can each comprise a
sensor which is arranged static relative to the cargo deck, in particular
on a frame of the freight transport devices. The freight transport
devices can comprise moving parts which for example move on re-alignment
of the roller. The determination of the position of the freight item can
be simplified if the sensors are arranged in a fixed pre-specified
position, in particular static, in relation to each other. To this extent
the individual positions of the sensors can be entered in the control
unit once and then remain constant thereafter. It is not necessary to
calculate the positions of the sensors as a function of the alignment of
the freight transport devices.

[0023] The signals received from the sensors can also give a coverage
pattern, wherein this coverage pattern allows the control unit to
establish which of the sensors are covered by a freight item. For light
sensors it would for example be possible to specify a degree of dimming.
Preferably the coverage pattern is a binary coverage pattern which allows
direct conclusions on the coverage (0 means that the corresponding sensor
is covered by the freight item, 1 means that the corresponding sensor is
not covered by a freight item).

[0024] To this extent the sensors can be allocated to the individual
freight transport devices. Preferably these sensors can be used to
establish whether a part of the freight item is located above the at
least one roller of the freight transport device, so that a transport
force can be applied by means of the roller. To this extent the sensors
have a double function. Firstly they serve to determine locally whether a
particular freight transport device can be used to transport the freight
item. Secondly the sensor is part of a group of sensors which together
allow determination of the position and/or movement of the freight item.

[0025] Preferably in the above embodiment example the freight transport
devices are arranged in a matrix, in particular regular. This matrix can
span the cargo deck preferably over the entire width in the loading and
unloading area. Also a regular arrangement can be applied in the
longitudinal direction. Preferably the matrix formed by the freight
transport devices is a substantially even matrix.

[0026] Preferably the sensors in particular to perform the former function
are arranged on the respective freight transport device surrounding the
at least one roller.

[0027] At least some of the freight transport devices can as already
specified be arranged in a matrix, preferably in the loading and
unloading area of the cargo deck. Preferably here a multiplicity of
freight transport devices is arranged which guarantee effective transport
of the freight item. Because of the precise control of the individual
freight transport devices it is no longer necessary, as described in the
prior art, to provide individual very powerful freight transport devices.
Rather several small freight transport devices can assume the function of
the large freight transport devices. Preferably the smaller freight
transport devices have a smaller construction height, for example less
than 10 cm, in particular less than 5 cm (2 inches). Such freight
transport devices can be provided in the hold without it being necessary
to provide additional drainage troughs below each freight transport
device. Because of the low height of the freight transport devices, which
can be installed without major modifications to the cargo deck, weight
and costs are saved. The seal of the hold floor remains unaffected and
possible interference with structures or systems below the floor is
avoided.

[0028] The matrix of freight transport devices according to the invention
preferably comprises at least 6, preferably at least 12 freight transport
devices.

[0029] The at least one freight transport device can comprise at least one
rotary table which is arranged in a frame rotatable about a vertical axis
and which accommodates at least one roller in order to adjust the roller
to transport the freight item in a specified transport direction. The at
least one roller of the freight transport device is mounted rotationally
mobile such that this can rotate within a plane running substantially
parallel to the cargo deck. To this extent it is possible to set any
angle so that freight items can be transported in any arbitrary
direction.

[0030] Preferably the sensors of the respective freight transport device
are arranged on the frame so that they stand still when the rollers are
swivelled. The position of the sensors therefore does not change, so that
from these the control unit can effectively determine the position of the
freight item.

[0031] Further sensors can be provided on the freight transport device, in
particular on the frame. For example these can be a temperature sensor,
in particular an infrared sensor. This temperature sensor can monitor the
temperature of the drive motor and/or the brake and/or the plates. Also
this temperature sensor can be arranged and designed such that it can
detect a temperature of passing freight items in order to detect in good
time a possible fire in the cargo. The temperature sensors can be in
communicative connection with the control unit so that the information
obtained can be passed on. For example it would be conceivable to provide
a corresponding warning system in the cockpit or in a floor station. The
warning can be given by an acoustic and/or visual signal (e.g. a horn
and/or warning light).

[0032] The freight loading system can comprise a read device, in
particular an RFID reader, to detect the freight item type and/or at
least one dimension, preferably a dimension of a base surface of the
freight item. To this extent it is possible when introducing the freight
item to detect information on the freight item so that this information
can be taken into account in determining the position of the freight item
on the cargo deck.

[0033] The read device can be used to detect additional or alternative
information on pallet size, weight, destination and/or a 2D or 3D
contour. These data can be stored in an RFID chip preferably integrated
in the freight item or attached to the load. Preferably the read device
is located in a door or entrance area of the aircraft deck in order
preferably to detect the data of a freight item entering the aircraft.

[0034] Preferably the control unit comprises a model generator to produce
an at least two-dimensional, preferably three-dimensional model of the
freight item and/or at least part of the hold of the aircraft. Using the
model produced it is possible to determine precisely the position of the
freight item on the cargo deck. The model of the hold can be used to move
the freight item automatically within the hold without a colliding with
elements of the hold or the aircraft fuselage.

[0035] The control unit can comprise a position memory device to store
position data in a temporal sequence which specifies the position of the
freight item on the cargo deck, wherein the control unit is designed to
determine the movement of the freight item from a determined actual
position and stored position data from the position memory device. As
already explained initially, preferably sensors are used which are
suitable only for position determination. By storing individual positions
in a temporal sequence, the movement of the freight item can be
determined. Preferably for this a corresponding model is generated so
that future positions can be predicted. The control unit is able to
process all information to determine the movement of the freight item.
For example control signals for the freight transport devices can be
taken into account.

[0036] The control unit can be designed to determine a nominal position
and an actual position of the freight item and control at least one
freight transport device such that the freight item is transported from
the actual position to the nominal position. The control unit thus
preferably implements an automatic process of transporting the freight
item.

[0037] The control unit can be designed to determine, instead of the
actual position and nominal position, a nominal transport direction for
at least one freight transport device. The freight transport device can
be designated a control freight transport device.

[0038] The control unit can be designed to determine, preferably in real
time, the relative movement of the freight item close to or at the
position at which the at least one roller of the first freight transport
device makes contact, and a nominal transport direction. Preferably the
roller is aligned taking into account the relative movement of the
freight item and the nominal transport direction. To this extent the
control unit can make an assessment taking into account firstly the
planned transport direction and secondly the friction of the roller.

[0039] The control unit can be designed to determine, from the actual
position and nominal position, a nominal transport direction for at least
one freight transport device, in particular the control transport device.

[0040] In this context the control unit can also be designed to determine,
taking into account the relative movement, an optimum transport direction
for at least one freight transport device, in particular the control
freight transport device, wherein when assuming the optimum transport
direction, the axis of the roller of the respective freight transport
device stands substantially perpendicular to the relative movement of the
freight item lying on the roller.

[0041] Furthermore the control unit can be designed to calculate a set
transport direction from the optimum transport direction and the nominal
transport direction, in particular as a weighted mean, and structure the
at least one freight transport device, in particular the control freight
transport device, according to the optimum transport direction. For the
actual setting of the freight transport devices in a particular
direction, for example the optimum transport direction, it is necessary
to take into account various parameters. Amongst others the actual
movement of the freight or freight item can be taken into account.
Furthermore the proposed transport direction, for example the direction
in which a freight item must be transported so that it is moved from an
actual position into a nominal position, is taken into account. Further
parameters such as inertia, torque etc. can influence the calculation.

[0042] In some embodiments a method for determining a movement of a
freight item on a cargo deck may be provided. The method may include the
following steps: determining of the dimensions and/or shape of a base
surface of a freight item by a control unit; receiving a multiplicity of
first signals from sensors which are arranged distributed over at least
part of the cargo deck and give the coverage by the freight item, at a
first time; calculating by the control unit of a first position of the
freight item from the first signals taking into account the dimension
and/or shape of the base surfaces of the freight item; storing of the
first position of the freight item in a memory; receiving of a
multiplicity of second signals from the sensors at a second time;
calculating by the control unit of a second position of the freight item
from the second signals taking into account the dimensions and/or shape
of the base surface; and calculating of the movement of the freight item
by comparison of the first position of the freight item with the second
position.

[0043] The at least one freight transport device can be aligned by the
control unit taking into account the movement of the freight item, in
particular the relative movement of the freight item, directly above the
freight transport device. Preferably the method according to the
invention comprises a corresponding alignment of the freight transport
device taking into account the calculated information.

[0044] Preferably a memory device of the control device contains position
data of the individual freight transport devices and the respective
sensor devices. These data allow the control device to allocate a
particular position on the cargo deck to each signal relating to a sensor
device. The signals thus give a position-related coverage pattern.

[0045] Also in the method according to the invention sensors are used to
detect the movement of the freight item. Preferably these sensors merely
indicate whether part of the freight item is above them. The control unit
can process the corresponding output signals to determine a position of
the freight item on the cargo deck. By recording these positions over
time, conclusions can be drawn in relation to the movement track of the
freight item.

[0046] A freight loading system for loading and unloading the cargo deck
may be provided. The system may include: a multiplicity of freight
transport devices each with at least one roller to transport freight
items in a transport direction, wherein the rollers of at least one first
freight transport device are mounted rotationally mobile such that the
transport direction of the first freight transport device can be
adjusted; and a control unit which receives signals from sensors to
detect a movement of a freight item, wherein the control unit is designed
to calculate from the signals a relative movement of a section of the
freight item relative to the first freight transport device and align the
at least one roller of the first freight transport device such that the
friction of the roller is minimised.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047]FIG. 1 a top view of part of a cargo deck with numerous freight
transport devices;

[0048] FIG. 2 a top view of a freight transport device in a first position
(set angle 0°);

[0049]FIG. 3 the freight transport device in FIG. 2 in a second position
(set angle 270°);

[0050]FIG. 4 the freight transport device in FIG. 2 in side view, wherein
the drive rollers are in a rest position;

[0051] FIG. 5 a side view of the freight transport device in FIG. 2,
wherein the drive rollers are in a drive position;

[0052]FIG. 6 a diagrammatic view of the freight loading system comprising
numerous sensors and actuators; and

[0054] An embodiment of the invention is described below by means of an
embodiment example which is explained in more detail with reference to
the figures.

[0055] In the description below the same reference numerals are used for
the same parts and those with similar effect.

[0056]FIG. 1 shows a top view of cargo deck 10 with a freight loading
system according to the invention. The part of the cargo deck 10 shown is
substantially rectangular and extends in the x-y plane (the y direction
corresponds to the longitudinal direction of the aircraft and the x
direction to the transverse direction) of the aircraft and is limited by
a left side wall 1 and a right side wall 2. The left side wall 1 is
interrupted in parts to form a door opening 7. Through this door opening
7 a freight container 30 shown in FIG. 7 can be introduced into the hold.
The freight loading system according to the invention is particularly
suitable for transporting bulky containers which must be rotated for
stowage within the hold. The freight loading system can however be used
in conjunction with clearly smaller freight containers 30 of any
dimensions. The freight container 30 shown in FIG. 7 has a length l which
is clearly longer than the width of the cargo deck 10 shown in FIG. 1 so
that the freight container 30 on loading must be rotated in the loading
and unloading area using the additional space offered by the door opening
7.

[0057] The cargo deck 10 of the aircraft shown in FIG. 1 is configured so
that a first freight loading track A and a second freight loading track B
are available to receive individual freight containers 30. For this along
a centre plane 5 of the cargo deck 10 are arranged centre locks 11, 11',
11'', 11'''. The freight loading tracks A, B have a width which
substantially corresponds to width b of the freight container 30. Usually
further function elements are provided to hold the freight container 30
suitably in the freight loading tracks A, B. The loading and unloading
area of the cargo deck 10 in FIG. 1 is equipped with twelve freight
transport devices 100, 110, 120, . . . , 210. These freight transport
devices 100, 110, 120, . . . , 210 are distributed over the loading and
unloading area. Preferably the freight transport devices 100, 110, 120, .
. . , 210 are distributed over the loading and unloading area so that a
freight container 30 to be loaded with a freight base contour 33, 33',
irrespective of its position, always covers at least two, preferably at
least three, freight transport devices 100, 110, 120, . . . , 210. In the
configuration shown in FIG. 1 the freight transport devices 100, 110,
120, . . . , 210 are arranged in a matrix comprising a multiplicity of
lines (in the x direction) and columns (in the y direction). Each line in
the configuration shown in FIG. 1 comprises three freight transport
devices 100, 110, 120, . . . , 210 and each column comprises four freight
transport devices 100, 110, 120, . . . , 210.

[0058] For the skilled person active in this field it should be evident
that an arbitrary other distribution of freight transport devices 100,
110, 120, . . . , 210 can be selected to achieve an extensive coverage of
the loading and unloading area. Thus four, five, six, eight or
substantially more freight transport devices can be installed in each
column or line. Furthermore it is possible to arrange the freight
transport devices 100, 110, 120, . . . , 210 in symmetrical and
asymmetrical configurations to fulfil the particular requirements of the
hold concerned. The regular configuration selected in FIG. 1 has the
advantage that the individual positions of the freight transport devices
100, 110, 120, . . . , 210 on the cargo deck 10 can easily be detected.
Nonetheless it would theoretically also be possible to use an arbitrary
network of freight transport devices 100, 110, 120, . . . , 210 to equip
the loading and unloading area and detect the corresponding positions.

[0059] Either side of the door opening 7 are arranged RFID readers 25, 25'
which can detect an RFID tag 34 on the freight container 30 (see FIG. 7).
To this extent, a control device 20 connected with the RFID reader 25,
25' is able to identify unambiguously an incoming freight container 30.
An identification number obtained can be used to determine the freight
container width b and length l, i.e. the dimensions, of the freight
container 30. Alternatively the RFID tag 34 can contain concrete
information on these dimensions. In a further embodiment example a laser
scanner can be arranged at the door opening 7 or at any other suitable
position to determine the dimensions of the incoming freight container
30.

[0060] The freight transport devices 100, 110, 120, . . . , 210 are
designed to transport the incoming freight container 30 and move it to a
prespecified position within the freight loading tracks A, B. In FIG. 1
the freight base contours 33, 33' are indicated diagrammatically. It is
evident that the already slightly oblique freight container 30 has been
shifted along the x axis in relation to the first freight base contour 33
by means of the freight transport devices 100, 110, 120, . . . , 210 in
order to assume the position shown by the second freight base contour
33'. The freight transport devices 100, 110, 120, . . . , 210 used can
for example be the type described in DE 198 07 229 A1. Preferably however
freight transport devices 100, 110, 120, . . . , 210 are used which have
a very low construction height so that their installation can be operated
at very low cost. Because of the control of the freight loading system
according to the invention it is possible to operate the shown number of
freight transport devices 100, 110, 120, . . . , 210 parallel to each
other such that the individual transport devices 100, 110, 120, . . . ,
210 need apply substantially less force. To this extent the desired
construction measures can be implemented without further action.

[0061] Freight transport devices 100, 110, 120, . . . , 210 used for
preference are explained in more detail below with reference to FIGS. 2
to 5. FIGS. 2 to 5 show example detail views of the freight transport
device 100. The freight transport device 100 has an annular frame 105 and
a circular rotation plate 103 arranged inside the frame 105. The rotation
plate 103 is mounted rotationally mobile within the frame 105 so that it
can rotate in the x-y plane about a rotation axis 106. The freight
transport device 100 has corresponding actuators and sensors so that the
rotation plate 103 can be aligned arbitrarily within the frame 105. The
sensors allow a conclusion on the alignment of the rotation plate 103
within the frame 105. FIGS. 2 and 3 show two different alignments of the
rotation plate 103.

[0062] The rotation plate 103 accommodates a roller drive unit 101 which
drives rollers 102a, 102b. Drive rollers 102a, 102b are designed to drive
freight items 30 in a direction transverse to the rotary axis of the
drive rollers 102a, 102b, substantially within the x-y plane. FIG. 2
shows the freight transport device 100 which is aligned such that it can
transport the freight in a first transport direction f1. For the skilled
person active in the field it will be evident that the freight items 30
can be driven in the opposite direction by driving the drive rollers
102a, 102b in the opposite direction of rotation. The alignment shown in
FIG. 2 is designated the base position and corresponds below to a zero
degree alignment. In contrast rotation plate 103 of freight transport
device 100 is twisted through 90° in FIG. 3 (set angle
270°) so that freight containers 30 can now be transported in the
second transport direction f2.

[0063] The preferred freight transport device 100 comprises furthermore
four sensor devices 104a, 104b, 104c, 104d arranged on the frame 105.
Thus the alignment of the rotation plate 103 does not influence the
position of sensor devices 104a, 104b, 104c, 104d. Preferably the sensor
devices 104a, 104b, 104c, 104d are each arranged on opposite sides of
frame 105. Thus the first sensor device 104a is in the 45° region
of the freight transport device 100, the second transport device 104b in
the 135° region, the third sensor device 104c in the 225°
region and the fourth sensor device 104d in the 315° region.
Sensor devices 104a, 104b, 104c, 104d are light sensors comprising
light-emitting diodes and photodiodes so that the sensor devices 104a,
104b, 104c, 104d are suitable for detecting the presence of a freight
item directly above sensor devices 104a, 104b, 104c, 104d.

[0064] As shown in FIGS. 4 and 5, the freight transport device 100 is
designed to swivel the drive rollers 102a, 102b from a rest position into
a drive position (FIG. 5). In the rest position the drive rollers 102a,
102b are lowered within the rotation plate 103 so that they no longer
protrude above the frame 105. In the drive position the drive rollers
102a, 102b protrude beyond the frame 105 and can drive freight items.
Swivelling between the rest position and the drive position is sensible
to avoid damage to the freight transport device 100 from a side collision
of a freight item with the drive rollers 102a, 102b. It is also possible
to modify the alignment of drive rollers 102a, 102b without material
friction by lowering them in a situation in which a freight item or
container 30 is standing directly above the freight transport device 100.
The sensors devices 104a, 104b, 104c, 104d can be used to establish
whether it is sensible to extend the drive rollers 102a, 102b from the
rest position into the drive position.

[0065] With the four sensor devices 104a, 104b, 104c, 104d it is possible
to detect whether a pallet is approaching the PDU in the transverse
direction. Thus it can be ensured that the PDU is lowered when driven
over by the load unit and only raised when the PDU is completely covered
(preventing side collisions).

[0066] Because of the arrangement of the individual freight transport
devices 100, 110, 120, . . . , 210 already described with reference to
FIG. 1, and the fact that each freight transport device 100, 110, 120, .
. . , 210 is equipped with corresponding sensor devices 104a, 104b, 104c,
104d, a network of sensor devices 104a, 104b, 104c, 104d is produced
which covers the loading and unloading area of the cargo deck 10
relatively densely.

[0067] The freight loading system according to the invention comprises the
control device 20 which is in communicative connection with the
individual freight transport devices 100, 110, 120, 210 and associated
sensor devices 104a, 104b, 104c, 104d to achieve an effective control of
the freight transport devices 100, 110, 120, 210.

[0068] The present invention uses the fact that because of the
multiplicity of sensor devices 104a, 104b, 104c, 104d present, the
position of the freight container 30 can be determined effectively. As
shown in FIG. 6, the control device 20 receives individual signals from
the respective sensor devices 104a, 104b, 104c, 104d via the freight
transport devices 100, 110, 120, 210. Furthermore it receives signals
from the RFID reader 25 giving the dimensions of the base 31 of freight
container 30. The control device 20 knows the positions of the individual
sensor devices 104a, 104b, 104c, 104d and can thus allocate the signals
to particular positions on the cargo deck 10. For the control device 20 a
coverage pattern results which indicates at which point one of the sensor
devices 104a, 104b, 104c, 104d of the freight transport devices 100, 110,
120, . . . , 210 is covered by the base 31 of the freight container 30.
Using this information the position of the freight container 30 on the
cargo deck 10 can be determined relatively precisely. If for example we
consider the freight base contour 33 which indicates a first position of
freight contour 30, it is clear that the first freight transport device
100, the second freight transport device 110, the third freight transport
device 120, the sixth freight transport device 150, the seventh freight
transport device 160, the eighth freight transport device 170 and the
twelfth freight transport device 210 are completely covered by the
freight container 30. To this extent the respective sensor devices 104a,
104b, 104c, 104d emit corresponding signals to the control device 20. As
the control device 20 knows the dimensions of the freight container 30,
the position of the freight container 30 can be determined relatively
precisely within particular tolerances. The memory device 21 can store
either the absolute positions of the sensor devices 104a, 104b, 104c,
104d of the respective freight transport devices 100, 110, 120, . . . ,
210. Alternatively relative position data can be present which for
example allow determination of the relative position of the freight
transport device 100 to freight transport device 110 or 120. In a further
alternative embodiment the relative positions can relate to the sensor
devices 104a, 104b, 104c, 104d. For example a relative datum with regard
to sensor device 104a of freight transport device 100 to sensor device
104a of freight transport device 110 can be stored. The skilled person
active in the field will be aware of numerous further possibilities for
storing corresponding position data on a memory device 21 so that the
control device 20 is able to determine, from the coverage pattern, the
position of the freight container 30 on the cargo deck 10.

[0069] For example using a model generator 22 a virtual image (two- or
three-dimensional) can be produced which is moved in a virtual model of
the sensor devices 104a, 104b, 104c, 104d (in particular the relative
position of the individual sensor devices 104a, 104b, 104c, 104d to each
other) until a virtual configuration results which would lead to a signal
pattern corresponding to the actual signals received from the sensor
devices 104a, 104b, 104c, 104d. Preferably the model generator 22 not
only generates the virtual network of sensor devices 104a, 104b, 104c,
104d but also takes into account further physical features of the hold
(e.g. side restrictions for example in the form of side walls 1, 2, the
position of door opening 7, existing function elements e.g. in the form
of lock elements etc.). Preferably the model generator 22 knows that when
loading freight container 30, only containers of certain standard
dimensions are used (e.g. 88×125 inch, 96×125 inch,
196×96 inch, 238.5×96 inch etc.). The control device 20 can
take this information into account when determining the position. Model
generator 22 can generate a complete three-dimensional model of at least
the loading and unloading area of the hold.

[0070] If now the freight container is driven so that its position
changes, as explained in relation to the second freight base contour 33',
a new coverage pattern of the freight transport devices 100, 110, 120, .
. . , 210 results. It appears that only the second freight transport
device 110, the sixth freight transport device 150, the seventh freight
transport device 160, the eleventh freight transport device 200 and the
twelfth freight transport device 210 are completely covered by the
freight container 30. The fifth freight transport device 140 and the
eighth freight transport device 170 have merely partial coverage. All
other freight transport devices 100, 120, 130, 180, 190 are not covered
by freight container 30. This second position of freight container 30 can
also be determined from the sensor devices 104a, 104b, 104c, 104d.
According to the invention the control unit 20 stores corresponding
position data in a memory device 21 and from the stored information
determines the movement of the freight container 30 on the cargo deck 10.
For the skilled person active in the field, it will be evident that the
control device 20 can receive a multiplicity of signals to perform a
substantially more detailed modelling of the movement of the freight
container 30. The sensor devices 104a, 104b, 104c, 104d are scanned at a
rate of at least 1 Hertz, preferably 10 Hertz or 100 Hertz, so that a
very precise position determination and/or modelling of the movement
processes can be performed. The control device 20 now uses this
information to adjust the freight transport devices 100, 110, 120, . . .
, 210 suitably. Thus the control device 20 can determine that the freight
container is moving over the second freight transport device with a
particular speed in a particular direction. In FIG. 1 this relative
movement r is indicated with the corresponding vector arrow. The control
device 20 can now align the second freight transport device 210 (e.g. to
a zero degree angle) so that the rotary axes of drive rollers 102a, 102b
stand substantially perpendicular to this determined relative movement r
so that an effective drive of freight container 30 is possible with
minimum wear. Furthermore freight transport devices 100, 110, 120, . . .
, 210 which are not yet covered by freight container 30 can already be
controlled so that they are already aligned suitably as soon as they are
covered.

[0071] Furthermore the information obtained with regard to movement of the
freight container 30 can be used to transport this semi- or fully
automatically into a desired position, for example in the freight loading
track B. Thus a user of the freight loading system according to the
invention can enter, for example via an input device 20, a desired
position for the freight container 30. The control device 20 thus knows
an actual position and a target position and can develop a corresponding
transport strategy to transport the freight container 30 from the actual
position into the target position. Thus the control device 20 can come to
the conclusion that the freight container 30 must be swivelled clockwise
out of the second position according to the second freight base contour
33' in order to park it in the freight loading track B. The control
device 20 can thus determine a nominal transport direction s for each
freight transport device 100, 110, 120, . . . , 210 covered by freight
container 30 and take this nominal transport direction into account when
controlling the freight transport device 100, 110, 120, . . . , 210. In
FIG. 1 the nominal transport direction s is symbolised by a corresponding
vector arrow. It would also be possible to stop the freight container 30,
align the second freight transport device and all further freight
transport devices concerned suitably, and then transport freight
container 30 further in a corresponding direction. Preferably however a
quasi-continuous transport of the freight container 30 takes place so
that there is no need to stop the freight container 30 for a direction
change. The control device 20 thus at a given time determines the
relative movement r for a particular freight transport device, for
example for the second freight transport device 110, and a corresponding
nominal transport direction s. From these values a setting of the freight
transport devices 100, 110, 120, 210 is determined which initiates a
suitable course correction. To this extent the freight container 30 is
swivelled continuously in the freight loading track B, wherein only a
very low wear occurs on the freight transport devices 100, 110, 120, 210.

[0072] In a preferred embodiment example the described configuration of
the cargo deck 10 with sensor devices 104a, 104b, 104c, 104d of the
respective freight transport devices 100, 110, 120, . . . , 210 is used
to produce a virtual image of the base 30 of the freight container and
compare this virtual image with stored two- or three-dimensional models
of the hold in order then to control the freight transport devices 100,
110, 120, 210, in particular the respective rotation plates 103
(direction of rotation of drive rollers 102a, 102b, alignment of rotation
plate 103) by calculation so that it is possible to rotate the freight
container 30 in the hold semi- or fully automatically. Preferably a
quasi-continuous control of the individual transport devices 100, 110,
120, . . . , 210 takes place, wherein their setting, in particular the
alignment of the rotation plate 103 during movement of the freight
container 30 is regulated to achieve as tangential a movement as possible
of the freight base 31 via the drive rollers 102a, 102b. This avoids
unnecessary wear.

[0073] It is possible to determine a two- or three-dimensional model of
the freight container 30 to be loaded on the basis of manual inputs. Thus
the freight loading system according to the invention can have stored for
example in the memory device 21 two- or three-dimensional models of all
common freight container types. It is possible for the user of the
freight loading system according to the invention to select the
corresponding freight container 30. Secondly the freight container type
can be detected automatically. With the freight loading system according
to the invention it is even possible to load freight containers 30 with
overlap. For example corresponding data suitable for producing a two- or
three-dimensional model of the freight container with overlap can be
stored on the said RFID tag 34. The control device 20 can determine an
optimum control plan from the model of the hold and the freight container
30 so that there is no collision of the freight container 30 with the
aircraft, in particular its outer skin.

[0074] In application of a suitable control strategy, preferably
corresponding fixed points are used so that the position and movement of
the freight item can be determined with great precision. For example
before entering the freight loading track B, the freight container 30 can
be aligned completely to function elements arranged along the right side
wall 2 opposite the door opening 7.

[0075] Although in the embodiment example described above the sensor
devices 104a, 104b, 104c, 104d are arranged on freight transport devices
100, 110, 120, . . . , 210, it would also be possible to provide some or
all of these separate from the freight transport devices 100, 110, 120, .
. . , 210. To this extent a network or grid of sensor devices 104a, 104b,
104c, 104d completely independent of freight transport devices 100, 110,
120, . . . , 210 could be established. [0076] Although the invention is
explained in the description above with reference to a cargo deck of an
aircraft, it can be used in conjunction with any arbitrary cargo deck
e.g. also in a logistics centre.